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I’m having a problem with a GFCI outlet that keeps tripping all of a sudden. I installed a garbage disposal and GFCI outlet under my sink seven years ago. The last few days every time I use the garbage disposal, GFCI will trip ~3-4s. later and flash red two times. I’m able to reset the outlet, but only to trip again if I use the disposal.

I’ve no clue why it’s tripping after seven years with no problem. Should I replace the outlet or is there something wrong with the disposal?

Thank you in advance!

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    If you use a heavy-duty extension cord to plug the disposal into a different GFCI, does said other GFCI trip? Does plugging other loads into the first GFCI trip it? – ThreePhaseEel May 11 at 0:24
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    Plug something else into the disposal outlet and see if it still trips running that load. Plug the disposal into another GFCI protected outlet and see if that outlet trips. Should narrow it down (unless neither case results in a trip when changed this way.) Edit: Hah - typing at the same time, thinking the same way. Hi TPE! – Ecnerwal May 11 at 0:24
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    Leaving as a comment as I have seen simple bathroom fans and range hood exhaust fans trip GFCI circuits dozens of times when the switch was turned off yes disposal units also this is caused from inductive kickback. It happens when the motor coils are no longer fed from mains power and there is a large inductive spike, this spike can be thousands of bolts and may trip gfci’s or damage them, yes at 7 years old the GFCI could be going bad but I would not expect a new motor to have anything other than kickback issues. – Ed Beal May 11 at 0:51
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Assuming that there is no other electric device connected to that GFCI - also not via a downstream/"load" outlet:

There might be a safety issue with that disposal, so taking care of the danger of electricity is mandatory.

Connecting the disposal to another GFCI outlet via an extension cable could disclose whether the disposal or the GFCI is defect.

The disposal or metal sink or other conducting material in connection with the disposal should not be touched, i.e. it should be switched on and the last step should be to plug in the extension cord into another GFCI outlet. To stop this test, the first step should be to unconnect the plug of the extension cord.

After some years, the electric isolation of the disposal could get worse due to humidity, dust, vibrations, grease/oil, acid etc.

The test button of the GFCI might show no problem, but that button can not test an over-sensitivity.

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  • Thank you everyone for your suggestions! I plugged the disposal using extension cord to another GFCI outlet, and it didn’t trip the outlet. I plugged in a low power device under the GFCI outlet and that didn’t trip the outlet. I’m assuming it’s because it’s low power? In conclusion, I would assume the GFCI outlet is broken and needs to be replaced? BTW, is it normal for GFCI outlets to go bad? I’ve installed other GFCI outlets that’s more than 10yrs old and never had any issues with any of them. – Reinnie May 11 at 4:33
  • Assuming a 3 wire cord, the GFCI seems to be defect resp. seems to have become too sensitive. The extension cord would even add some more current from line to ground via it's capacitance, i.e. an extension cord should increase the probability for a GFCI to interrupt the power. Yes, a GFCI can be damaged by a short. Or maybe some dust/water/mold has settled on the internal surfaces of the GFCI outlet. A cleaning with non-ionic fluids like destilled water or isopropanol and careful drying may help. Detergents or soap should not be used. The test button must be working after re- installation. – xeeka May 11 at 10:50
  • Thank you so much! – Reinnie May 12 at 1:47

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